Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2~7
This invention relates to a process for manufacturing
polyurethane-coated products wherein a metal substrate is
press-formed into a core member of a desired shape and then the
core member is covered with polyurethane foam.
This type of process, wherein a metal substrate is
press~:Eormed into a core member of a desired shape and there-
after the desired portions of the core member are covered with
polyurethane foam, is applied to the manufacture of bumpers
and the like as well as internal automotive trim parts such as :
lQ instrument panel pads, seats, overhead consoleboxes, door trims,
armrests, kneepads and the like.
For example, when the instrument panel pad is manufac-
ture~ by press~forming a metal substrate in-to a core member of
a desired sha~e and then covering the surface of the core menlber
with polyurethane foam, it has hitherto been practised that the
metal substrate (us~ally steel plate or galvanized s-teel plate),
which is coated with a rust preventing oil for preventing the
generation of rust during transportation or stora~e, is first
subjected to blanking, coated with a press-forming lubricant
(high-viscosity lubricant composed mainly of a mineral oil, for
e~ample, trade ma~k "G 634" made by Nippon Kosakuyu Kabushiki
Kaisha or the like) and then press-formed into a desired shape.
Then, the thus press-formed metal substrate is covered at
desired surface portions with polyurethane foam to form a
core member (which is usually called an insert member). In order
to obtain satisfactory adhesion between -the core member and -the
polyurethane coating, however, it is believed to be important
that the rust preventin~ oil previously adhered to -the steel
surface and the press-forming lubricant applied before the
press-forming are completely removed from the surface of the
A ^' ~
~:f~J
~5S~Z07
core member and hence a degreasing step is required. The order
of production steps for the instrument panel pad is shown in the
following Table 1. Such prior art production schedules have
drawbacks as mentioned below:
1. The production order is complicated. (A number of steps
are required which are labor intensive.)
2. For satisfactory adhesion between the press-formed core
member and the polyurethane a degreasing and cleaning
step for com~letely removing the rust preventing oil and
the press-forrning lubricant is necessary as mentioned
above.
3. Since the press-forming lubricant frequently has a high
viscosity so as to improve the drawing operation,
partial degreasing or insufficient degreasing and the like
may occur. As a result~ much labor and time are required
to complete the degreasing step.
The degreasing step is commonly considered by those
skilled in the art to be essential because it is generally
necessary to ef~ect a pretreatment for surface degreasing
and cleaning prior to adhering the polyurethane, as shown in r
~or example, Handbook of Adhesive Technology, Nikkan Kogyo
Shinbunsha, July 1963, p. 18 et seq. and Polyurethane Resin,
Nikkan Kogyo Shinbunsha, 1969, pp 115 and 239. That is, the
concept that the degreasing step is an essential step to ensure
complete adhesion is widely accepted in -the art. As a result,
there are no methods in the prior art which omit the degreasing
step.
In general, the surface of the metal substrate, which
is an adherend, is frequently covered with a thin film of an
oxide or a hydroxide, or may adsorb various substances.
Further, the surface of the adherend is usually contaminated
with oils used for rust prevention~ oils used for cutting or
rolling, and the like. Usually~ these oils are removed with a
solvent, a detergent, an acid or an alkali because they adhere
to the adherend in large quantities and considerably reduce
the adhesive strength. In the case of using a solvent, however,
the partly adhered oil may be spread o~er the whole surface of
the adherend, 50 that repeated washing is required by succes-
sively exchanging the used solvent for fresh solvent. Further,
in the case of using an alkali or detergent, these substances
remain at the surface of the adherend and hence may reduce the
adhesive strength.
It is, therefore, an object of the invention to overcome
or mitigate the above-mentioned drawbacks of the conventional
production system, by omitting the degreasing step from the
production steps. ~
According to an embodiment oE the invention there is -
provided a process for manufacturing polyurethane-coated pro~
ducts comprising the steps of(a) coating a metal substrate
with a lubricant inclusive of a compound having an oxygen-
hydrogen bond;(b) press-forming the coated metal substrate into
a core member of a desired shape;(c) applying to the core mem- ~
ber at least a polyol and an isocyanate as polyurethane forming ~;
raw materials and reacting t~le raw materials to form poly-
urethane and reacting isocyanate groups with the oxygen-hydrogen
bond compound whereby the core member is coated with poly-
urethane; wherein steps (a) to (c) are effected without de-
greasing the metal substrate. Often step~c) comprises applying
to the core member at least a polyol, an isocyanate and a blow-
ing agent as polyurethane forming raw materials and reacting
the raw materials to form polyurethane and reacting isocyanate
. ~
~5~;~07
groups with the oxygen-hydrogen bond compound, whereby the core
member is coated with polyurethane foam.
The term "oxygen~hya~gen bond" used herein means to
include a hydroxyl group, a carboxyl group and the like, which
are capable of reacting with the isocyanate group in the for-
mation of polyurethane. For convenience 7 sake, the invention
.
1~
:: 20
-3a-
......
2~7
wil]. be described with reference to the compound having a
hydroxyl group below.
The invention will be described in grea~er detail with
respect to the manufacture of instrument panel pads. The
production steps of the invention are shown together with
those of the prior art in Table 1.
~ ~ a
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A ¦ I 1~ , ~t+~ ~ I
b h ~ ~ ~ r~ ~t i Lr) I
~' .
~L~LS~
A lubricant containing hydroxyl yroup is first applied to
a metal substrate, which is then press formed into a core
m~mber of a desired shape. In this case, the lubricant used
is a solid lubricant and/or a polyol oil.
As the solid lubricant, there is preferably used a high
molecular weight lubricant developed by H. A. Montgomery C.orp.
(trade name "MIL-BOND")~ whose composition is described in
Japanese Patent Application Publication No. 3,702/76.
In another preferred embodiment, various substances, for .
example~ so-called polyols including a polyfunctional alcohol
may be added to the solid lubricant~ Various kinds of polyol
oil can be used, an example of which is EX-169SB (trade name,
made by Asahi Denka Kogyo Kabushiki Kaisha).
In one embodiment, commercially available steel plates,
coated with the solid lubricant which acts as both a rust
preventing agent during transportation and a lubricant for
press-forming of the steel plate, may be press worked as they
are. However, if only the rust pre~enting oil is thinly applied
to the metal substrate, the lubricant according to the invention
is applied prior to the press working.
After a skin material is placed in a mold, the core member 7
obtained by press-forming as described above/ is located at a
given position in the mold and thereafter a polyurethane foam
forming composition is poured in-to the mold, and foamed for a
given time, whereby a foam structure comprising the skin and
the core member coated with polyurethane Eoam is manufactured.
In the manufacture of the instrument panel pad, the
steel plate is used as a core member because a pad composed only
of the skin and foamed polyurethane has poor rigidity and the
attachment thereo~ is very difficult. As the skin material,
~L~S9~1~37
there is usually used vacuum formed semi-rigid ABS sheet
blended with vinyl chloride or slush molded vinyl chloride.
Skin formed by the application of vinyl chloride sol or skin
made from the foamed polyurethane itself (so-called integral
skin) may also be used.
The polyurethane foam is produced by the reaction of a
polyol, an isocyanate and a blowing agent, which are properly
selected in accordance with the use of the foam. The following
methods are available for injecting and foaming the composition
in the rnold:
(1) Foaming-in-place method under a relatively low pressure,
i.e. hot curing of the selected composition by heating
during the foaming or cold curing of the composltion at
room temperature; and
(2) Rapid foaming method under pressure, i.e. RIM (Reaction
Injection Molding). This method is not used in the
manufacture oE instrument panel pads.
The degreasing step and various steps associated there
with, which have been required in the prior art, can be omitted
by using a core member formed by press-forming the metal
substrate coated with the lubricant inclusive of a compound
having a hydroxyl group and then the desired surface portions
of the core member are coated with polyurethane foam. Thus,
it is possible to produce a polyurethane elastomer having
satisfactory adhesion between the core mer,lber and the
polyurethane and a quality equal to or better than that of the
prior art. A possible mechanism for the adhesion between the
core member and the polyurethane foam is considered below:
The adhesion between the polyurethane foam and the metal
substrate takes place via the isocyanate, which is a reactant
l;' ~
~L5~ 7
for the production of polyurethane, and which adheres to metal,
silicate, rubber or the like. It is known that the isocyanate
forms a primary chemical bond by direc-tly bonding to hydroxide
generated by the hydrolysis of an oxide Eilm present on the
surface of the metal substrate. Furthermore, i~ is considered
that the isocyanate reacts with water adsorbed on the surface
of the metal substrate to cause further adhesion. l~he press-
forming lubricant to be used in the invention contains a
compound having a hydroxyl group, which is able to react with
the starting materials for polyurethane or has an affinity for
the starting materials for polyurethane, as mentioned above,
so that it is considered that even if the press-forming lubricant
layer is existent on the surface of the metal substrate, the
bonding between the polyurethane foam and the metal surface is
not only achieved, but also the lubricant itself forms a
urethane bond with the isocyanate to increase the adhesion
between the polyurethane and the metal surface.
On the contrary, when the press-forming lubricant
composed of mineral oil is applied as in the prior art, the
mineral oil has only a few or no terminal reactive groups
(carboxyl group, hydroxyl group), so that it does not react
with the isocyanate. Moreover, it obstructs the approach of
the isocyanate to the surface of the metal substrate and the
formation of so-called urethane bonds between the isocyanate
and the hydroxide present on the metal surface or water adsorbed
on the metal surface~ and as a result the bonding between the
formed polyurethane foam and the metal substrate is not
satisfactory. Further, the conventional pressing lubricant is
usually higher in viscosity and is applied at a thicker gauge,
,30 so that it is very difficul-t to incorporate the isocyanate or
- 8 -
~L~S~Z07
polyol into this lubricant and consequently the bonding between
the polyurethane and the metal is more obstructed. Therefore,
it is eonsidered that the degreasing step is essential in the
prior art.
~ nbodiments of the invention will now be deseribed in
greater detail with reference to the accompanying drawings,
wherein:
Fig. 1 is a sectional view of an instrument panel pad
manufactured by the process according to the invention; and
Fig. 2 is a sectional view illustrating the molding state
of the instrument panel pad according to the invention.
The invention will be described with reference to the
following examples, comuarative examples and ex~eriment. In
these examples, all parts and percentages are by weight, unless
otherwise stated.
Example 1
This example shows -the manufaeture of an instrument panel
pad 1 as shown in section in Fig. 1.
. ~
The instrument panel pad 1 is securel to the upper
surfaee of an instrument panel 3 by means of bolt 4 and nut 5,
and serves as a shock absorbing member. In this fi~ure t
numeral 6 is a cJlove box and numeral 7 is a lid therefor. The
pad 1 has a strueture wherein foamed polyurethane 9 is filled
between a pressed eore member 2 and a skin material 8.
In the manufaeture of the instrument panel pad 1, a
eommereially available solid lubrieant MIL-BOND MC 560 (trade
mark, made by Ni~pon Oil and Fats Co., Ltd.), with a composition
eonsisting of 20 parts of eommereially available aerylie aeid
eomposed of 80% polyaerylie aeid ancl 20~ methacrylic aeid, 3
parts of styrene-maleic anhydride eopolymer, 0.5 part of caleium
_ g ._
~5~2()7
stearate, 0.5 part of zinc stearate and sufficient methylene
chloride to make up to 100 parts, was applied to a steel plate
in an amount of 3-5 g/m2~evenly 4 g/m ). The thus treated
steel plate was blanked and press-formed into the core member 2.
In this case, the drawability of the steel platc was at a
level equal to or higher than that when using a conventional
press oil (for example, commonly used high viscosity lubricant
composed of mineral oil).
As shown in Fig. 2, the skin material. 8 (com~osed of a
blend of vinyl chloride with acrylonitrile-buta~iene-styrene
terpolymer resin) was placed in the bot-tom part 11 of a mold 10, .
while the core member 2, which was not degrea~ed, was held by
magnets 13, 13' located at given positions of -the top par-t 12 of
mold 10. Then a composition for forming polyurethane foam 9 ~-
having a compounding recipe as shown in the following Table 2
was injected into the space defined by the skin material 8 and
the core member 2 and then reacted under such conditions as
shown ln the following Table 3 to obtain an instrument panel
pad provided with a skin.
~:
2Q TABLE 2
Ingredients Compounding amount
(parts)
PPG3000 tri.ol *1 85
Pluracol PeP 450 *2 15
TMBDA *3 2
T - 9 *4 Q~05
L - 5310 *5 2
Acryloid - 710 *6 0.2
Water 4
30 Mondur MR *7 (isocyanate index 105) 95
-- 10 --
Note: * 1 ..~ trade mark of polyol ~molecular
weight: 3000, OH value: 56) made by
Union Carbide Corp.
* 2 ... trade mark of polyether polyol made by
Wyandotte Chemical Corp.
* 3 ... N,N,N',N"-tetramethylene-1,3-butane
diamine as a catalyst, made by Union
Carbide Corp.
* 4 ... trade mark of a catalyst, made by
Union Carbide Corp~
* 5 ... trade mark of a blowing accelerator,
made by Union Carbide Corp.
* 6 ... trade mark of a cell opening agent,
made by Rohm & Haas Cou
* 7 ... trade mark of dimethylmethane diisocyan-
ate (NCO: 31.5 - 32.0%~ viscosity: 200
50 cp at 25o, acidity: '0~2%, vapor
pressure at 25 C: lx10-3 mmHg), made
by Mobay Chemical Corp.
TABLE 3
Mechanical production conditions
Mold temperature 43 - 49 C
Curing time 5 - 10 minutes
Foaming machine Model, made by ~`~
Mobay-Hennecke Corp.
Agitator pin type
Mixlng low shear
Agitating speed 5000 rpm
Mixer size length 100 x diameter
50 mm
Mixer capacity about 200 cc
Resin temperature 26C
Isocyanate temperature 26 C
Example 2
A steel plate was first coated with the solid lubricant
MIL-BOND MC 560 in an amount of 3-5 g/m and then blanked. An
~., ~,.,
'
activator for the solid lubricant composed of 90 parts of a lard
oil and 10 parts of butyl cellosolve, which is recommended as
a second coating layer, was then applied by means of rolls and
then scraped off with a doctor blade so that the coated amount
was not mor~ than 0.5 g/m . The thus treated steel plate was
press-formed into the core member 2 with satisfactory
drawability.
Then, the core member 2, which was not degreased, and
skin material 8 were placed in the mold 10 and the polyurethane
foam 9 was formed around the core mernber 2 in the same manner
as described in Example 1 to obtain the instrument panel pad .
1 shown in Fig. 1.
Example 3 :
To the steel plate covered with the solid lubricant in the
same manner as de~cribed in Example 1 was applied an oil agent
composed mainly of polyols, EX-1695~ (trade mark, made by
Asahi Denka Kogyo Kabushiki Kaisha) i.n an amount of 0.5 g/m2
by means of rolls. Thereafter, the steel plate was blanked
: and press-formed into the core member 2. This core member 2
was set in the mold 10 without degreasing and coated with the
polyurethane foam 9 in the same manner as described in Example 1
~o obtain the instrument panel pad 1.
~xarnple 4
.
A comrlercially available steel plate coated w.ith a solid
lubricant composition 0.2 ~ thick was blanked and press-formed
into the core member 2. This solid lubricant composition
contained 55% of solid paraffin, 20% of di-long chain alkyl
ketone, 5% of fatty acid, 5% of glycerin fatty acid monoester and
15% of addition product of alkylphenol with 7 moles of ethylene
- 12 -
l .-.~,
5 ~5,~3ZO~
oxide as described in Japanese Patent laid open No. 60,3~0/78.
The thus obtained core member 2 was set in the mold without
degreasing as recommended by the manufacturer of the steel
plate and then an instrument panel pad 1 provided with -the core
member 2, the polyurethane foam 9 and the skin material $ of
vinyl chloride was manufactured in the same manner as described
in Example 1.
Example_5
To a steel plate (coated with a very thin film of a
paraffinic rust preventing oil) was applied a polyol oil
composed mainly of polyol (trade mark "EX-1695B", made by Asahi
Denka Kogyo Kabushiki Kaisha) in an amount of ~ g/m2 in order to
achieve pressing-l.ubrication. The thus treatecl stecl. plate was
blanked and press-formed into the core member 2, which was then
made without degreasing into the instrument panel pad 1 in the
same manner as descri~ed in Example :l.
Example 6
A coating solution composed of the same solid lu~ricant
as described in Example 1 and containing S~ of polyol was
applied to a steel plate in an amount of 3-S g/m . The thus
treated steel plate was blanked and a coating solution of
ethylene glycol was applied thereto in an amount of 2-3 g/m
so as to form a resin-activated coating layer. Thereafter,
the steel plate was press-formed into -the core member 2. The
core member 2 was used without degreasing to manufacture the
instrument panel pad 1 in the same manner as described in
Example 1.
,.~. . ~
~l~L59Z~)7
Example 7
A steel plate covered with the same solid lubricant as
described in ~xample 1 was press-formed into the core member 2
without the application of the usual press-forming oil composed
of high viscosity mineral oil. The thus obtained core member 2
was subjected to a painting finish with -the following paint
without degreasing and then set in the mold 10. Thereafter, the
instrument panel pad 1 provided with the polyurethane foam 9 was
manufactured in the same manner as described in Example 1.
The painting finish as described above is to ensure a
desirable appearance on the product locally covered with the
foam.
The paint was a two-component polyurethane paint
requiring no heating, which was a mixture of 130 parts of
DesModur N (trade mark, made by Bayer ~.G., 75%) and 100 parts
of Desmophen #800 (~rade mark., made by Bayer A.G.). As the
coloring agent, inorganic pigments, dyestuffs and t~e like
were used.
Comparative Example 1
.
A steel plate was coated with a rust preventing oil
composed of a spindle oil (An-tirust P2100, trade mark, made by
Nihon Sekiyu Kabushiki Kaisha) and blanked. The thus treated
steel plate was further coated with a conventional press-forming
lubricant composed of high viscosity mineral oil (for example,
paraffinic oil ~660 made by Nippon Kosakuyu Sha or the like) in
the minimum required amount and then press-formed into the
core member 2.
The thus obtained core member 2 was placed in-to the
mold 10 without being degreased and then the polyurethane foam 9
- 14 -
.~ ,.- .
! ~
~L~Lr~ 7
was formed together with the skin material 8 composed of a
blend of vinyl chloride-~BS resin in the same manner as
described in Example 1 to obtain the instrument panel pad 1.
Comparative Example 2
A steel plate coated with the same solid lubricant as
used in Example 1 was press-formed into a core member 2 and then
spray degreased under the following conditions:
Degreasing conditions: 1.5~ of Ridorin #16 made by
Nippon Paint Kabushiki Kaisha,
pH = 10.2, bath temperature =
55 - 65Cr spraying pressure =
2 kg/cm2, time = 2 minutes.
After the degreasing solution was thoroughly washed
off, the wettability of the steel surface was visually confirmed
by the presence of water repelling. Thereafter, a sufficiently
clean surface of the steel plate was obtained by drying~
The subsequent procedure was rep~eated in the same manner
as described in Comparative Example 1 to obtain the instrument
panel pad 1.
Co~parative ExamEle 3
A steel plate coated with the same solid lubricant as
described in Example 1 was press-formed into the core member 2
in the same manner as described in Example 7. The thus obtalned
core member was degreased under the same conditions as described
in Comparative Example 2 prior to the painting finish. ~fter
the surface of the core member was confirmed to be clean by
thoroughly washing the degreasing solution with water, the
core member was painted with the same two-component polyurethane
paint as described in Example 7. The thus painted core member 2
- 15 -
~' .
~591;~7
was placed in the mold 10 and the polyurethane foam 9 was formed
therearound to obtain the instrument panel pad 1.
Experiment
The adhesion state between the core member 2 and the
polyurethane foam 9 and the bonding state of the paint coating
in Example 7 and Comparative Example 3 were examined with
respect to the instrument panel pads of Examples 1-7 and
Comparative Examples 1-3. The results are shown in the
following Table 4.
- 16 -
~L~ 5~2~)7
_ __ I__ __ _._ __ o ` ,,,
~x ~ ~
.~ l~ o o ~ o o ~o~
_ _ i : .
, o - o ~ ~ o ~ ', J- I o o `
`D X O I ,C j O ~ ~ ~.
Q~ u~ X lt- O a~ ~,~ `',_ ~ -- o ~ ra ~ :
:~ X ~ o o ~ I ~ ~ ~
_~ ~_ .,~ o ~ o ~
~ ~ ~7 x O ~ ~ ,a~ ~
~ ___ i ~' ~ __ ,~
: ~ ~I X O ~0 ~ ~ ~D O r~
: _ ___ ~ ~ 1~ E ~__ U o ~ r
: a o_ :
~ ~ ~ ~ C ~ A ~ ~I X
c ~ ~ ~ ~ L ~ o
O~,c c a~ I Ock !
cc: ~ ~ ~ ! Q~
a ~ ~ a, ~ ~ O I ~a X
-- 17 --
ZO~ ~
Note: * l ... Nichiban masking tape #241 made by
Nichiban Kabushiki Kaisha
* 2 ... The failure state is not a failure
between the metal and the foam layer but
a cohesive failure of the foam layer.
Therefore, the adhesion is sufficiently
held.
* 3 ... The foam adhesion is dependent upon the
foam density. The measured values of
the foams in Examples 1-6 were equal to
those described in the articles, so that
there was no lowering of the foam
strength by the omission of the degr~as-
ing step.
* 4 ... A U-shaped notch was formed in the
polyurethane foam (about lO mm thick)
adhered on the steel plate (1.6 mm
thick) so as the notch reached the sur-
face of the steel plate. Separately,
~20 ~ there was provided an L-shaped steel
plate. This L~shaped steel plate was
inserted into the U-shaped notch until
`
the short side of the L-shaped steel
plate touched the surface of the steel
plate. Thereafter, the adhesion between
the steel plate and the foam was
measured by peeling off the foam in a
direction perpendicular to the steel
plate. In the measuremen-t, a spring
balance may conveniently be used.
- 18 - -
~5912~37
In this case, the failure state
is a so-called cohesive failure of the
foam layer, which shows that the
adhesive strength between the steel
plate and the foam is larger than the
strength of the foam.
* 5 O~ Adhesive test of the paint coating
according to JIS K-5400.
From the data o Table 4, it can be seen that the
adhesion between the core member and the polyurethane foam
in the products of Examples 1-7 is sufficient ~or practical
use even though the degreasing step is omitted. The reason why
the satisfactory result is obtained in each ~xample is considered
as follows.
In ExamplPs 1 and 7, the solid lubricant consisting mainly
of acrylic acid and applied to the steel plate can provide
sufficient adhesive s'crength to the polyurethane-coated product ;
;~ because acrylic acid is usable as a vehicle for paint and
~; effectively acts as an adhesive between the polyurethane foam
layer and the metal layer~ That is, the terminal carboxyl
groups (-COOH~ of acrylic acid contribute not only to the
formation of hydrogen bonds with the metal, but also to the
formation of crosslinking bonds with isocyanate groups (-NCO).
Further, acrylic acid readily dissolves, permeates and diffuses
in polyol, so that it is partly incorporated into the resultlng
polyurethane foam through the polyol and by its reaction with
the isocyanate it may be considered to strengthen the direct
adhesion between the foam and the metal. Further, various
inter-molecular forces supplementally increase the adhesive
strength.
-- 19 --
~:!`.t
9;~ 7
In Examples 2 and 6, lard oil or ethylene glycol is
applied on the solid lubricant of Example 1. However, the
adhesion is hardly affected by the lard oil or ethylene glycol,
because the lard oil contains carboxyl groups ( COOH), while
ethylene glycol contains hydroxyl groups (-OH) and these groups
form urethane bonds with isocyanate groups, so that the lard oil
or ethylene glycol constitutes a part of the polyurethane foam
after the foaming.
In Example 3, the polyol oil is applied -to the surface of
the metal, but it contains polyol capable of forming urethane
bonds with isocyanate groups, so that the polyol oil does not
prevent the adhesion between the metal and the foam.
In Example 4, additive ingredients other than solid
paraffin, i.e. long chain alkyl ketones, fatty acids, glycerin
monoesters of fatty acids and alkylphenols all containing
carboxyl or hydroxyl groups capable of reacting with isocyanate
groups are used, so that these ingredients constitute a part of
the resulting polyurethane foam. Therefore r the additive
ingredient portions of the solid lubricant contacting with the
metal surface are incorporated in the foam and hence the metal
directly adheres to the foam. If this solid lubricant is thinl~
applied to the metal, paraffin fuses by the heat of formation
of urethane bonds and incorporates into -the foam, so that the
area of the foam contacting with the metal surface is increased
and hence the adhesion is improved.
In Example 5, the paraffinic rust preventing oil is
thinl~ applied to the steel plate, but this oil fuses by the
heat of formation of urethane bonds and incorporates into the
foam as mentioned above, so the adhesion is not influenced by
the rust preventing oil.
- 20 -
,~
~ .
~5~207
The product of Comparative Example 1, not only has
propert.ies which are inferior to those of Example 1 as apparent
from Table 4, but the foam layer easily peels from the metal.
From this fact it is understood that the omission of the
degreasing step is very de-trimental when using the ].ubricant as
descr.ibed in Comparative Example 1. Moreover, it can be seen ;
that when the coating of high viscosity press-forming oil is
removed by using a warmed alkaline degreasing solution under the
following conditions and then the metal is washed with water and
dried, the adhesive strength can be improved up to an extent
substantialIy equal to that of Example 2.
Degreasing conditions: Ridroin #53S made by Nippon Paint
Kabushiki Kaisha, spraying
pressure - 1 kg/cm2,
temperature = 65-70C
As apparent from Table 4, the product of Comparative
Example 2 shows good ,~dhesion, while the product of Comparative
Example 3 after the completion of curirlg shows a bonding state,
of the paint coating, equal to that of Example 7 according to
the cross cut test. However, the degreasing step includes many
problems such as the need for degreasing equipment and
accessories, degreasing agents, maintenance of degreasing bath
temperature, pressurized spraying or dipping, rinsing treatment,
disposal o~ rinsed waste liquid and the like. From this view-
point, it is apparent that the process of the invention omitting
the degreasing step is industrially superior to the prior art
requiring the degreasing step.
Although the invention has been described with respect
to an instrument panel pad formed by covering a metal core
30 member with polyurethane foam, i-t will be apparent to those .
- 21 -
~9
~S~ 7
skilled in the art that various changes and modifications may
be made without departing from -the scope of the invention. For
instance, the invention is applicable not only to the manufacture
of other automotive parts such as armrests, crush pads, sun
visors, steering wheels and the like, but also the manufacture
of so-called polyurethane integral skinned foams, i.e. -those
formed by foaming the core material inside a skin made from the
foaming resin solution.
- 22 -
~.''
